1. Field of the Invention
The present invention relates to a surface-mounted electromagnetic sound generating body incorporated in mobile communications devices, such as cellular phones and pagers, that generates an incoming call indicator tone when the device receives an incoming call, and more particularly to a thin surface-mounted electromagnetic sound generating body mounted on the surface of a printed circuit board or the like in a mobile communications device.
2. Description of the Prior Art
A known example of the surface-mounted electromagnetic sound generating body 1 of this kind includes a thin type which incorporates a vibrating sound generating unit (not shown) in a rectangular parallelepiped resin casing 2, as shown in FIG. 1.
The surface-mounted electromagnetic sound generating body 1, as shown in FIG. 2, is incorporated in a body case 3 of a mobile phone, for example, and mounted on a printed circuit board 4. The casing 2 has a sound release hole 5 formed on a front side. The sound generating body 1 is surface-mounted on the printed circuit board 4 so that the sound release hole 5 faces an opening 6 formed in one part of the body case 3. A sound leakage prevention packing 7 is installed in a gap between the sound release hole 5 of the surface-mounted electromagnetic sound generating body 1 and the opening 6 in the body case 3 to prevent an incoming call indicator tone released from the sound release hole 5 from being trapped in the body case 3. This packing 7 has a hollow portion 7a to accommodate the entire casing 2 of the surface-mounted electromagnetic sound generating body 1, and a through-hole 7b that communicates the sound release hole 5 with the opening 6. After the electromagnetic sound generating body 1 is mounted on the printed circuit board 4, the packing 7 is fitted over the casing 2 from above. The inner side of the body case 3 around the opening 6 is bonded with a dust prevention cloth 8 to prevent dust, foreign matters, water droplets and humid air from entering into the body case 3. The packing 7 is installed in the body case 3 with the front side of the packing pressed against the dust prevention cloth 8.
FIGS. 3 and 4 show another example of the conventional packing 9. The packing 9 has a hollow portion 9a covering the front half of the casing 2 and a through-hole 9b for communicating the sound release hole 5 to the opening 6. The packing 9 also has a double-sided adhesive tape 10 attached to the side of the hollow portion 9a around the through-hole 9b. When a mobile phone is assembled, a cover sheet is removed from the double-sided adhesive tape 10, which is then bonded to the periphery of the sound release hole 5 to fix the packing 9 to the casing 2.
With the conventional surface-mounted electromagnetic sound generating body 1 described above in the first and second examples, however, because the body 1 and the packing 7 or 9 are supplied separately to the mobile phone assembly line, the packing 7 or 9 must be attached, in a separate process, to the casing 2 of the body 1 surface-mounted on the printed circuit board 4.
Further, because the packing 7, 9 is formed as a cover that encloses the entire or front half of the casing 2, the volume occupied by the surface-mounted electromagnetic sound generating body 1 on the printed circuit board 4 increases, giving rise to a problem of greater limitations in mounting other parts.